Roentgen discovered X-radiation by the inadvertent exposure of a silver halide photographic element. In 1913, Eastman Kodak Company introduced its first product specifically intended to be exposed by X-radiation (X-rays). Silver halide radiographic films account for the overwhelming majority of medical diagnostic images. It was recognized almost immediately that the high energy ionizing X-rays are potentially harmful, and ways were sought to avoid high levels of patient exposure. Radiographic films provide viewable silver images upon imagewise exposure followed by wet processing.
One approach, still in widespread practice is to coat a silver halide emulsion useful in radiographic films on both sides of the film support. Thus, the number of X-rays that can be absorbed and used for imaging are doubled, providing higher sensitivity. Dual-coated radiographic films are sold by Eastman Kodak Company under the trademark DUPLITIZED. Films that rely entirely on X-radiation absorption for image capture are referred in the art as "direct" radiographic elements, while those that rely on fluorescent intensifying screen light emission are referred to in the art as "indirect" radiographic elements.
Direct radiographic elements have various uses, such as in industrial applications where intensifying screens cannot be used for some reason (for example pipeline welds and turbine blades).
Another important application for direct radiographic elements is in dentistry where images of a patient's teeth and gums are made in order to provide desired diagnostic and preventative dental care. In dental diagnostic imaging a small piece of X-ray film, commonly referred to as "chip" mounted in a sealed opaque package is placed in a patient's mouth during X-ray exposure.
Copending and commonly assigned U.S. Ser. No. 09/007085 filed Jan. 14, 1998 by Baugher et al now U.S. Pat. No. 5,952,163, describes direct dental X-ray films that can be removed from the opaque packages after imagewise exposure and processed in room light. Those films are comprised of silver halide emulsion and protective layers that contain dye particles that can be decolorized during wet processing.
Copending and commonly assigned U.S. Ser. No. 09/087477 filed May 29, 1998, now U.S. Pat. No. 5,925,505, also describes and claims direct dental X-ray films that can be handled in ambient light.
Dental X-ray film is used worldwide in providing dental care. In many countries that are less industrialized or are considered "emerging" markets, cost of dental care is a great concern because of limited resources by dentists for purchasing materials and supplies. Many patients in those countries cannot pay for such services despite their need for them. As a result, there is a need to provide dental X-ray films that are less expensive, can be used with existing or lower cost processing systems, and that still provide desired sensitometric properties (for example, speed).